April 14, 2009

Population centers at low elevations like Florida's Key West are vulnerable to sea-level rise. Credit: NOAA

The threat of global warming can still be greatly diminished if nations cut emissions of heat-trapping greenhouse gases by 70 percent this century, according to a new analysis. While global temperatures would rise, the most dangerous potential aspects of climate change, including massive losses of Arctic sea ice and permafrost and significant sea level rise, could be partially avoided.

The study, led by scientists at the National Center for Atmospheric Research (NCAR), will be published next week in Geophysical Research Letters. It was funded by the Department of Energy and the National Science Foundation, NCAR's sponsor.

"This research indicates that we can no longer avoid significant warming during this century," says NCAR scientist Warren Washington, the lead author. "But if the world were to implement this level of emission cuts, we could stabilize the threat of climate change and avoid catastrophe."

Avoiding dangerous climate change

Average global temperatures have warmed by close to 1 degree Celsius (almost 1.8 degrees Fahrenheit) since the pre-industrial era. Much of the warming is due to human-produced emissions of greenhouse gases, predominantly carbon dioxide. This heat-trapping gas has increased from a pre-industrial level of about 284 parts per million (ppm) in the atmosphere to more than 380 ppm today.

With research showing that additional warming of about 1 degree C (1.8 degrees F) may be the threshold for dangerous climate change, the European Union has called for dramatic cuts in emissions of carbon dioxide and other greenhouse gases. The U.S. Congress is also debating the issue.

To examine the impact of such cuts on the world's climate, Washington and his colleagues ran a series of global supercomputer studies with the NCAR-based Community Climate System Model. They assumed that carbon dioxide levels could be held to 450 ppm at the end of this century. That figure comes from the U.S. Climate Change Science Program, which has cited 450 ppm as an attainable target if the world quickly adapts conservation practices and new green technologies to cut emissions dramatically. In contrast, emissions are now on track to reach about 750 ppm by 2100 if unchecked.

The team's results showed that if carbon dioxide were held to 450 ppm, global temperatures would increase by 0.6 degrees C (about 1 degree F) above current readings by the end of the century. In contrast, the study showed that temperatures would rise by almost four times that amount, to 2.2 degrees C (4 degrees F) above current readings, if emissions were allowed to continue on their present course.

Holding carbon dioxide levels to 450 ppm would have other impacts, according to the climate modeling study:

Sea level rise due to thermal expansion as water temperatures warmed would be 14 centimeters (about 5.5 inches) instead of 22 centimeters (8.7 inches). Significant additional sea level rise would be expected in either scenario from melting ice sheets and glaciers.

Arctic ice in the summertime would shrink by about a quarter in volume and stabilize by 2100, as opposed to shrinking at least three-quarters and continuing to melt. Some research has suggested the summertime ice will disappear altogether this century if emissions continue on their current trajectory.

Arctic warming would be reduced by almost half, helping preserve fisheries and populations of sea birds and Arctic mammals in such regions as the northern Bering Sea.

Significant regional changes in precipitation, including decreased precipitation in the U.S. Southwest and an increase in the U.S. Northeast and Canada, would be cut in half if emissions were kept to 450 ppm.

The climate system would stabilize by about 2100, instead of continuing to warm.

The research team used supercomputer simulations to compare a business-as-usual scenario to one with dramatic cuts in carbon dioxide emissions beginning in about a decade. The authors stressed that they were not studying how such cuts could be achieved nor advocating a particular policy.

"Our goal is to provide policymakers with appropriate research so they can make informed decisions," Washington says. "This study provides some hope that we can avoid the worst impacts of climate change--if society can cut emissions substantially over the next several decades and continue major cuts through the century."

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15 comments

Lol, Denialist.... Thats EXACTLY what the Inquisitors called people who didn't believe 100% of the Churches teachings or thought that maybe Copernicus or Galileo or other early scientists might be on to something...

So no stupid (this means you John balls)... no one on my side of the aisle, the side of science and observation and study of empirical data and analysis of trends that span geological time denies that global warming happens. We deny one thing and one thing only, that the science is all in and that there is complete 100% agreement that man-made greenhouse gas production is DEFINITELY going to destroy the entire biosphere of the earth, all within the next century.

That's what we deny... care to tie us all up and burn us at the stake? Yeah you do don't you... ignorant fear-addled primitive that you are.

"The research team used supercomputer simulations to compare a business-as-usual scenario to one with dramatic cuts in carbon dioxide emissions ..."

In other words, it's all BS based on PlayStation Climatology. If you instead study the data for the last 450,000 years you do not come to any sort of disaster scenario at all - unless you consider returning to an ice age, which is possible. These clowns can't tell me the weather next week with any accuracy and yet they'll purport to tell me what's going to happen a 100 years from now. BS.

Lol, Denialist.... Thats EXACTLY what the Inquisitors called people who didn't believe 100% of the Churches teachings or thought that maybe Copernicus or Galileo or other early scientists might be on to something....

Oh my goodness, horrible analogy. Comparing the church which is based on an imaginary sky God to actual scientist that use evidence to back a claim which is "peer reviewed" is quite a stretch to say the least. Religion is static science is not.

So no stupid (this means you John balls)... no one on my side of the aisle, the side of science and observation and study of empirical data and analysis of trends that span geological time denies that global warming happens. We deny one thing and one thing only, that the science is all in and that there is complete 100% agreement that man-made greenhouse gas production is DEFINITELY going to destroy the entire biosphere of the earth, all within the next century..

You don't even know what the definition of denialist actually means judging by your ridiculous response.

Denialist can be defined as someone who does not believe AGW not someone that argues what the ill effects this will have on our world. You fail again.

.

That's what we deny... care to tie us all up and burn us at the stake? Yeah you do don't you... ignorant fear-addled primitive that you are.

HA!

I love the fact the experts in the field are overwhelming in consensus on AGW but you guys, the arm chair rethugs have some how figured it out.

Since the denialist know so much and clearly appear to know more then the "experts" in the field and then you guys should start to publish your work and have it peer reviewed.lollololololo... oh that%u2019s right your not climatologist. And lololol you have no evidence or original thoughts to be peer reviewed.

You guys and your religion just crack me up. Even the leaders of your church of propaganda are slowly starting to see the light.

You guys are no different then the nuts that don't believe in evolution.

I don't want to hear you so called arm chair expert advice that you have some evidence that some how all the worlds experts are overlooking. If this is the case please do the scientific community a favor and publish your work.

Hey Quibit, the only primitive on here is you. Because, clearly I got under your skin by simply using a term that best describes your ignorant mind.

Looking over the data for CO2 there has not really been that substantial an increase over the last three years. That said, looking over the temperature data shows that we have been on a downward trend for the last three years.

Winter 2008 was dubbed "the coldest winter of the 21st Century." Denialists thus far have good ground to deny much of what the IPCC and tribe of Gorians say.

So far, looking over the data it looks like it is going to be another colder year. Record lows were reached for this time of year in a number of places in the Northern Hemisphere just last week. Where is the unfalsifiable evidence of AGW? I have yet to see it.

Whatever side of the assorted issues you are on doesn't really matter. If your primary concern is that you want mankind to survive, then we must continue forward...even if we damage the Earth's ecosystem, or even destroy it, in the process.

The authors of this article want to cut the production of GH gases by 70% just to make a 2 inch difference in the purported sea level rise in a century. Whether the 70% is a cut from current or future GH gas production is not clear. Either way, it means slowing down human activity and/or spending huge amounts of effort on finding alternative methods of production that release 70% less GHG.

If we take the slow approach, I think we are doomed for various reasons. We would be "stuck" at our current level with no way to move forward without first engineering new technologies that pass the litmus test of Environmental Conservatives. At our current speed of developement, it could take a thousand years to do what could be done in a century with exponential increases. During that time, countless other dangers could strike us down or set us back(plague, meteor, GRB, global cooling, etc.)

If we stay on our current course, the rate of developement of new technologies will accelerate, and simply by the act of living and building and creating, the way we naturally do, we will be in a better position to protect ourselves.

As for the Earth. I consider it to be our nest. Baby birds don't stop eating or go on a diet just because they are worried about pooping up the nest. They are compelled to eat, eat, eat, until they can leave the nest and fend for themselves.

Once we have the power to leave the nest, then we will have the LUXURY of saving the Earth's ecosystem, if we choose. More likely, we will be engineering the Earth to suit our desires, but if enough people want to return it to 100% natural condition for the off chance that another species will rise up and dare to fly, so be it.

Along the way, it will be advantageous to study the Earth and learn all we can. Whenever we see chances to go with more "green" technologies, without going way out of our way, by all means, go for the green. All of the knowledge we gather now will pay off later when we do see clear and efficient ways to fix known problems.

I think that, one day, scientists will look back and say that it is a natural progression for a species that attains sentience, intelligence, and sapience, to continue its developement beyond the scope of its birth environment, often at the cost of that environment. We are not apart, above or beyond nature. We are natural beings and we are pursuing the next level of existence. I, for one, wish to continue.

Want to know the funniest thing about this article? It begins by mentioning Florida's Key West but then uses a blurred picture of New Orleans in the aftermath of Katrina!!! HAHAHAHAA! And the NOAA gets the credit in the article for the photo! What does that say about the NOAA, if true?

It also turns out that cutting CO2 may not be a good thing at all. According to scientists at Caltech there is not enough CO2 in the atmosphere to counteract the increase of solar radiation coming in a billion or so years. These same scientists also say that in order to compensate we will need to remove nitrogen from and decrease the pressure of the atmosphere in order to compensate for the loss of CO2.

As the sun has matured over the past 4.5 billion years, it has become both brighter and hotter, increasing the amount of solar radiation received by Earth, along with surface temperatures. Earth has coped by reducing the amount of carbon dioxide in the atmosphere, thus reducing the warming effect. (Despite current concerns about rising carbon dioxide levels triggering detrimental climate change, the pressure of carbon dioxide in the atmosphere has dropped some 2,000-fold over the past 3.5 billion years; modern, man-made increases in atmospheric carbon dioxide offset a fraction of this overall decrease.)

The problem, says Joseph L. Kirschvink, the Nico and Marilyn Van Wingen Professor of Geobiology at Caltech and a coauthor of the PNAS paper, is that "we're nearing the point where there's not enough carbon dioxide left to regulate temperatures following the same procedures."